Polyphase shunt commutator motor



P 1 B. ADKINS 2,295,319

POLYPHASE SHUNT COMMUTATOR MOTOR Filed Jan. 8, 1942 Fig. I.

Inventor I Ber'hard Adkins,

His ttor'ney.

. narcissism:

UNITED STATES PATENT OFFICE :95.319 ronr'rmisn sum comuu'm'ron moron Bernard Adkins, Rugby, England, minor to General Electric Company, a corporation of New York Application Januarg 8, 1942, Serial No. 426,085 In Entlan January 28, 1941 My invention relates to improvements in the control of poLvphase shunt commutator motors.

The polyphase shunt commutator motor when controlled by a double induction regulator, gives a low power factor compared with an induction motor if the regulator voltage in phase with the motor secondary voltage, because of the reactance oi the induction regulator.

while the quadrature component in the extreme position depends on the diflerence in angular movement.

The two regulators maybe coupled together by means of gears, chains or belts, for example, two worm wheels of unequal size may engage with worms mounted on a common shaft. Alternatively they may be coupled by means of straps, wii'es'or chains attached to disks on the regulator shafts and arranged to give the limited angular movement required.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention reference is made in the-following description to the accompanying drawing, in which Fig. 1 represents a physical embodiment of my invention, and Fig. 2 an explanatory vector diagram pertaining thereto.

In 1, represents a polyphase shunt commutator motor having its stator energized from a suitable power line I I. I have represented a double induction regulator connected between the power supply I I and the commutator brushes it of the polyphase machine III for speed regulation. and power factor correction. The primary windings of the regulator are represented at A: and I3 connected in parallel to the supply lines i i and I have represented them as similar stationary windings. The secondary adjustable windings of the induction motor are represented at it and Ii connected in series to the commutator brushes l6. rotating the secondary windings or the induction regulator with respect to the primary wind- 55 tor for regulating the speed or said motor, each 10 and the resultant is at a minimum value.

35 ing component should that be desirable.

ll represents a mechanism for ings in the usual manner except that the secondary windings are rotated by unequal amounts. Asrepresented winding It will be rotated at a faster rate than winding l5. Also, winding i5 5 has more turns than winding H and, hence produces the greater secondary voltage.

In Fig. 2, let 03 represent the voltage produced by winding i5 and 00 the voltage produced. by winding I 4 when such voltages are bucking The diilerential voltage is equal to CB and is in a direction at right angles to the speed control volage axis and is, therefore, available for power factorimprovement oi motor to.

Now, as the regulator is adjusted to produce a speed control voltage, the vector OB moves through a range 0B to DB while vector 0C 'moves through a range 0G to 0C". In the extreme position, vectors 0C" and 0B" add and the speed regulating component is C"D". In the intermediate position the voltage regulating com"- ponent is C'l).

It will be noted that such an arrangement maintains a power factor improving component which is substantially constant through the roanlating range and is designated in the three post tions as CE, DB and IL B" and. this is accom plished with negligible sacrifice of the speed voltage regulating range. For instance, the

(3D" is very little shorter than the line ()"Pf.

If winding it were rotated at a still faster rate with respect to winding it: than as repre sented, the power factor improvement component could be made to increase with the speed regulat Likewise, it could be made to decrease with an in crease in the speed regulating component. The relative magnitude of the power factor impror ing component can be changed by changing the relative length of the'voltage vectors 0C and ary voltage and an unequal rate of adjustment of f the rotary elements of the two parts of the regulator. But, it is immaterial to the invention whether the primary or secondary windings be e made unequal and unequally adjustable.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, a polyphase shunt commutator motor, a power supply therefor, a pair of induction regulators connected between said source of supply and the commutator of said moof said regulators having relatively rotatable primary and secondary windings, the primary windings being connected to the source of supply and the secondary windings being connected in series to the commutator of said motor, one of said regulators producing a higher secondary voltage than the other, and common means for producing relative rotation between the primary and secondary windings of the regulator with the higher secondary voltage at one rate and between the primary and secondary winding of the other regulator at a relatively greater rate such that a variable speed regulating voltage is delivered to the commutator oi said motor, which has a comr ponent for power factor correction throughout the range of regulation.

2. In a regulating system, a pair oi. induction regulators forming a double induction regulator. said regulators having relatively rotatable primary and secondary windings with dlflerent transformation ratios and common regulating means for producing relative rotation between the primary and secondary windings of said regulators at unequal rates, the regulator having the higher transformer ratio having the lowest regu lating rate.

BERNARD ADKINS. 

